This is not easy for newbies and casual users that just want their own private
boomarking site. It also makes it really easy to miss the dozens other
configuration options that are not part of the config.php.dist file
but are only declared in config.default.php. A better way for setup
would be:

Download release from Sourceforge onto server

Unzip

Open URL in webbrowser

Wizard notices no config file exists and leads you through installation,
asking for database credentials and allowing to configure further options.

This way of installing SemanticScuttle would make installation less
error-prone and more pleasing.

Now instead of writing an installer yourself, there could be tools somewhere
out in the web that already to this, right? Something like
NSIS,
IzPack
or WiX,
just for PHP web applications? Something like
PEAR post-installation
scripts, just not only for the command line?

There are some of them, but not a single one that I liked. To save you
your own investigation, here is a list of them.

Desired feature set

Here is a list of features I would expect or wish to be in such a
setup/configuration tool:

General features

Automatically detect if the application has been setup.

Preferably lives in/generates a single php setup script file. If not, it needs to live in an own directory.

Security

lock installation tool to my IP address

require creation of file to proceed with installation

ask for install password that has been written in a non-webaccessible file on the server

remove write rights from whole application directory after installation, if wished even from config file

Interface

Existing tools

Tools I found out there on the web, in no particular order.
The only actively developed one costs money, all others are or seem to be dead.
The commercial one has no features the others don't have either.
Plus, all of them do only database setup and file permissions - nothing else.